Evaluation of skin absorption of drugs from topical and transdermal formulations

ABSTRACT The skin barrier function has been attributed to the stratum corneum and represents a major challenge in clinical practice pertaining to cutaneous administration of drugs. Despite this, a large number of bioactive compounds have been successfully administered via cutaneous administration because of advances in the design of topical and transdermal formulations. In vitro and in vivo evaluations of these novel drug delivery systems are necessary to characterize their quality and efficacy. This review covers the most well-known methods for assessing the cutaneous absorption of drugs as an auxiliary tool for pharmaceutical formulation scientists in the design of drug delivery systems. In vitro methods as skin permeation assays using Franz-type diffusion cells, cutaneous retention and tape-stripping methods to study the cutaneous penetration of drugs, and in vivo evaluations as pre-clinical pharmacokinetic studies in animal models are discussed. Alternative approaches to cutaneous microdialysis are also covered. Recent advances in research on skin absorption of drugs and the effect of skin absorption enhancers, as investigated using confocal laser scanning microscopy, Raman confocal microscopy, and attenuated total reflectance Fourier-transform infrared spectroscopy, are reviewed.

Screening of the Receiving Solution in Transdermal Absorption of Jiufen Spray / 中药新药与临床药理

Objective: To screen the receiving solution used to study the transdermal absorption of strychnine in Jiufen spray. Methods: With recovery,Q-T equation and transdermal speed constant as the parameters, the improved Franz-cell and the skin of SD rats were used to screen the receiving solution from saline, saline-alcohol (7∶3,v∶v), pH phosphate buffer solution-alcohol (88∶2,v∶v), pH 7.4 phosphate buffer containing 25% alcohol. Results: The comparison of the inter-day and intra-day recoveries,Q-T equation and transdermal speed constant showed that saline-alcohol(7∶3) was the best for the study. Conclusion: It is indicated that saline-alcohol(7∶3) was the best receiving solution for the transdermal absorption study of Jiufen spray.